#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include <locale.h>
#include <limits.h>
#include <wchar.h>

#include <time.h>

#include "putty.h"
#include "charset.h"
#include "terminal.h"
#include "misc.h"

/*
 * Unix Unicode-handling routines.
 */

int is_dbcs_leadbyte(int codepage, char byte)
{
  return 0; /* we don't do DBCS */
}

int mb_to_wc(int codepage,
             int flags,
             const char *mbstr,
             int mblen,
             wchar_t *wcstr,
             int wclen)
{
  if (codepage == DEFAULT_CODEPAGE) {
    int n = 0;
    mbstate_t state;

    memset(&state, 0, sizeof state);

    while (mblen > 0) {
      size_t i = mbrtowc(wcstr + n, mbstr, (size_t)mblen, &state);
      if (i == (size_t)-1 || i == (size_t)-2)
        break;
      n++;
      mbstr += i;
      mblen -= i;
    }

    return n;
  } else if (codepage == CS_NONE) {
    int n = 0;

    while (mblen > 0) {
      wcstr[n] = 0xD800 | (mbstr[0] & 0xFF);
      n++;
      mbstr++;
      mblen--;
    }

    return n;
  } else
    return charset_to_unicode(
        &mbstr, &mblen, wcstr, wclen, codepage, NULL, NULL, 0);
}

int wc_to_mb(int codepage,
             int flags,
             const wchar_t *wcstr,
             int wclen,
             char *mbstr,
             int mblen,
             const char *defchr,
             int *defused,
             struct unicode_data *ucsdata)
{
  /* FIXME: we should remove the defused param completely... */
  if (defused)
    *defused = 0;

  if (codepage == DEFAULT_CODEPAGE) {
    char output[MB_LEN_MAX];
    mbstate_t state;
    int n = 0;

    memset(&state, 0, sizeof state);

    while (wclen > 0) {
      int i = wcrtomb(output, wcstr[0], &state);
      if (i == (size_t)-1 || i > n - mblen)
        break;
      memcpy(mbstr + n, output, i);
      n += i;
      wcstr++;
      wclen--;
    }

    return n;
  } else if (codepage == CS_NONE) {
    int n = 0;
    while (wclen > 0 && n < mblen) {
      if (*wcstr >= 0xD800 && *wcstr < 0xD900)
        mbstr[n++] = (*wcstr & 0xFF);
      else if (defchr)
        mbstr[n++] = *defchr;
      wcstr++;
      wclen--;
    }
    return n;
  } else {
    return charset_from_unicode(&wcstr,
                                &wclen,
                                mbstr,
                                mblen,
                                codepage,
                                NULL,
                                defchr ? defchr : NULL,
                                defchr ? 1 : 0);
  }
}

/*
 * Return value is TRUE if pterm is to run in direct-to-font mode.
 */
int init_ucs(struct unicode_data *ucsdata,
             char *linecharset,
             int utf8_override,
             int font_charset,
             int vtmode)
{
  int i, ret = 0;

  /*
   * In the platform-independent parts of the code, font_codepage
   * is used only for system DBCS support - which we don't
   * support at all. So we set this to something which will never
   * be used.
   */
  ucsdata->font_codepage = -1;

  /*
   * If utf8_override is set and the POSIX locale settings
   * dictate a UTF-8 character set, then just go straight for
   * UTF-8.
   */
  ucsdata->line_codepage = CS_NONE;
  if (utf8_override) {
    const char *s;
    if (((s = getenv("LC_ALL")) && *s) || ((s = getenv("LC_CTYPE")) && *s) ||
        ((s = getenv("LANG")) && *s)) {
      if (strstr(s, "UTF-8"))
        ucsdata->line_codepage = CS_UTF8;
    }
  }

  /*
   * Failing that, line_codepage should be decoded from the
   * specification in conf.
   */
  if (ucsdata->line_codepage == CS_NONE)
    ucsdata->line_codepage = decode_codepage(linecharset);

  /*
   * If line_codepage is _still_ CS_NONE, we assume we're using
   * the font's own encoding. This has been passed in to us, so
   * we use that. If it's still CS_NONE after _that_ - i.e. the
   * font we were given had an incomprehensible charset - then we
   * fall back to using the D800 page.
   */
  if (ucsdata->line_codepage == CS_NONE)
    ucsdata->line_codepage = font_charset;

  if (ucsdata->line_codepage == CS_NONE)
    ret = 1;

  /*
   * Set up unitab_line, by translating each individual character
   * in the line codepage into Unicode.
   */
  for (i = 0; i < 256; i++) {
    char c[1];
    const char *p;
    wchar_t wc[1];
    int len;
    c[0] = i;
    p = c;
    len = 1;
    if (ucsdata->line_codepage == CS_NONE)
      ucsdata->unitab_line[i] = 0xD800 | i;
    else if (1 == charset_to_unicode(
                      &p, &len, wc, 1, ucsdata->line_codepage, NULL, L"", 0))
      ucsdata->unitab_line[i] = wc[0];
    else
      ucsdata->unitab_line[i] = 0xFFFD;
  }

  /*
   * Set up unitab_xterm. This is the same as unitab_line except
   * in the line-drawing regions, where it follows the Unicode
   * encoding.
   *
   * (Note that the strange X encoding of line-drawing characters
   * in the bottom 32 glyphs of ISO8859-1 fonts is taken care of
   * by the font encoding, which will spot such a font and act as
   * if it were in a variant encoding of ISO8859-1.)
   */
  for (i = 0; i < 256; i++) {
    static const wchar_t unitab_xterm_std[32] = {
        0x2666, 0x2592, 0x2409, 0x240c, 0x240d, 0x240a, 0x00b0, 0x00b1,
        0x2424, 0x240b, 0x2518, 0x2510, 0x250c, 0x2514, 0x253c, 0x23ba,
        0x23bb, 0x2500, 0x23bc, 0x23bd, 0x251c, 0x2524, 0x2534, 0x252c,
        0x2502, 0x2264, 0x2265, 0x03c0, 0x2260, 0x00a3, 0x00b7, 0x0020};
    static const wchar_t unitab_xterm_poorman[32] =
        L"*#****o~**+++++-----++++|****L. ";

    const wchar_t *ptr;

    if (vtmode == VT_POORMAN)
      ptr = unitab_xterm_poorman;
    else
      ptr = unitab_xterm_std;

    if (i >= 0x5F && i < 0x7F)
      ucsdata->unitab_xterm[i] = ptr[i & 0x1F];
    else
      ucsdata->unitab_xterm[i] = ucsdata->unitab_line[i];
  }

  /*
   * Set up unitab_scoacs. The SCO Alternate Character Set is
   * simply CP437.
   */
  for (i = 0; i < 256; i++) {
    char c[1];
    const char *p;
    wchar_t wc[1];
    int len;
    c[0] = i;
    p = c;
    len = 1;
    if (1 == charset_to_unicode(&p, &len, wc, 1, CS_CP437, NULL, L"", 0))
      ucsdata->unitab_scoacs[i] = wc[0];
    else
      ucsdata->unitab_scoacs[i] = 0xFFFD;
  }

  /*
   * Find the control characters in the line codepage. For
   * direct-to-font mode using the D800 hack, we assume 00-1F and
   * 7F are controls, but allow 80-9F through. (It's as good a
   * guess as anything; and my bet is that half the weird fonts
   * used in this way will be IBM or MS code pages anyway.)
   */
  for (i = 0; i < 256; i++) {
    int lineval = ucsdata->unitab_line[i];
    if (lineval < ' ' || (lineval >= 0x7F && lineval < 0xA0) ||
        (lineval >= 0xD800 && lineval < 0xD820) || (lineval == 0xD87F))
      ucsdata->unitab_ctrl[i] = i;
    else
      ucsdata->unitab_ctrl[i] = 0xFF;
  }

  return ret;
}

const char *cp_name(int codepage)
{
  if (codepage == CS_NONE)
    return "Use font encoding";
  return charset_to_localenc(codepage);
}

const char *cp_enumerate(int index)
{
  int charset;
  charset = charset_localenc_nth(index);
  if (charset == CS_NONE) {
    /* "Use font encoding" comes after all the named charsets */
    if (charset_localenc_nth(index - 1) != CS_NONE)
      return "Use font encoding";
    return NULL;
  }
  return charset_to_localenc(charset);
}

int decode_codepage(char *cp_name)
{
  if (!cp_name || !*cp_name)
    return CS_UTF8;
  return charset_from_localenc(cp_name);
}
